brainpopfandomcom-20200223-history
Genetic Mutations/Transcript
Transcript Text reads: The Mysteries of Life with Tim and Moby A boy, Tim, and a robot, Moby, are walking outside. Tim reaches down and picks a four-leaf clover. TIM: Look, a four-leaf clover. MOBY: Beep. Moby is holding an eight-leaf clover. TIM: Whoa. Tim reads from a typed letter. TIM: Dear Tim and Moby, What's a genetic mutation? From, Andy. TIM: Genetic mutations are permanent changes to a cell's DNA or RNA. Deoxyribonucleic acid and ribonucleic acid are the chemical blueprints for your entire body. Side-by-side images show DNA, or deoxyribonucleic acid, and RNA, or ribonucleic acid. An image shows a blueprint sketch of a human body. TIM: Every living organism has genetic material that controls all of its body's function. This material also determines physical traits. The double helix strand of DNA appears over several small images showing different types of life forms, including fish, fruit, animals, plants, humans, and insects. TIM: Some, like eye color, are completely controlled by your genes, while others, like height, are a product of genes plus environment. An image shows a brown human eyeball. A second image shows a human silhouette having its height measured. TIM: Sometimes, the genetic code changes. An image shows the original strand of DNA. An animation shows a strand of mutant DNA, which looks slightly different from the original. MOBY: Beep. TIM: Well, most of these changes do nothing at all. They're corrected by DNA repair, so they don't become permanent mutations. An animation shows a damaged piece of DNA repairing itself, chaning back to the original form. TIM: But when mutations do become permanent, they're usually deleterious, or bad. Cells depend on thousands of proteins to work properly. Mutations can mess up the genes that are responsible for making these proteins. An animation shows a single cell with several parts. The cell parts grow, change shape, and damage the cell. TIM: For example, sickle-cell anemia, a blood disease, is caused by a very small mutation in a protein-encoding gene. An image compares a healthy red blood cell with a mishaped one affected by sickle-cell anemia. TIM: Cancer is the result of deleterious mutations that cause uncontrolled cell growth. An animation shows normal human cells. Cancer cells appear quickly and form a large mass. The mass is labeled "tumor." TIM: Occasionally, a mutation is beneficial and helps an organism survive. Beneficial genetic mutations are thought to be one of the driving forces of evolution. Side-by-side animations show a woodpecker with a very short beak trying unsuccessfully to get a worm out of a hole in a tree, alongside a long-beaked woodpecker who is able to reach a similar worm in a similar hole. TIM: That's the process that makes organisms change over a number of generations. An image shows a silhouette of an ape, which splits into two. One of them remains on all fours, while the other changes shape and walks upright. TIM: Organisms with beneficial mutations survive better and are more likely to pass on their mutated genes. Side-by-side images show the short-beaked woodpecker with no worm to feed its three sad nestlings alongside the long-beaked woodpecker feeding a worm to its three excited nestlings. MOBY: Beep. TIM: Oh, mutations can be caused by lots of different things. Sometimes they happen spontaneously, or randomly, during cell division. An animation shows a cell dividing into two. TIM: Mutation can also be caused by outside forces, like chemicals, radiation, and viruses. Images show a chemical beaker, a radiation symbol, and a virus. TIM: Wow, that's kinda neat. Tim and Moby look down at the ground, where several eight-leaf clovers are growing from a single plant. As they watch, three new shoots appear. Each produces a different piece of odd fruit. TIM: Hey, hey, maybe we should tell some scientists about this thing. Moby reaches down and pulls the plant from the ground. Then he throws his head back and eats the plant. TIM: What? How? Whoa, whoa! Why did you do that? You're weird! Category:BrainPOP Transcripts